Multistage pump body and multistage gas pump

Abstract

A multistage pump body comprises a first pumping chamber ( 20 ) and a second pumping chamber ( 21 ). A connecting duct ( 26 a ) puts an outlet ( 27 ) of the first pumping chamber ( 20 ) into communication with an inlet ( 28 ) of the second pumping chamber ( 21 ). A leak-tight conduit ( 40 ) is provided for the circulation of a cooling liquid. The connecting duct ( 26 a ) is a lateral duct of the multistage pump body. A heat-conducting wall ( 33 ) partially delimits the connecting duct ( 26 a ) and has an external surface ( 34 ) on the outside. At least a portion of the connecting duct ( 26 a ) passes between this external surface ( 34 ) of the heat-conducting wall ( 33 ) and the leak-tight conduit ( 40 ).

The invention claimed is: 
     
       1. Multistage pump body, comprising at least:
 a first pumping chamber, 
 a second pumping chamber, 
 an axial passage for a rotating shaft, said axial passage connecting the first and second pumping chambers and defining a radial direction that is perpendicular to a longitudinal axis of the axial passage, 
 a connecting duct putting an outlet of the first pumping chamber into communication with an inlet of the second pumping chamber, wherein the connecting duct is a lateral duct of the multistage pump body which comprises at least a heat-conducting wall partially delimiting the connecting duct and having an external surface on an outside, and 
 a leak-tight conduit for circulation of a cooling liquid, at least a portion of the connecting duct passing between the external surface of the heat-conducting wall and the leak-tight conduit, 
 wherein at least a portion of the leak-tight conduit is disposed between the connecting duct and at least one of the first and second pumping chambers in the radial direction. 
 
     
     
       2. Multistage pump body according to  claim 1 , wherein at least a further portion of the leak-tight conduit passes between the first pumping chamber and the second pumping chamber. 
     
     
       3. Multistage pump body according to  claim 1 , further comprising at least one heat-conducting partition separating the connecting duct and the leak-tight conduit from one another. 
     
     
       4. Multistage pump body according to  claim 1 , further comprising at least one heat-conducting partition separating the leak-tight conduit and the first pumping chamber from one another. 
     
     
       5. Multistage pump body according to  claim 1 , wherein the leak-tight conduit partially wraps around the first pumping chamber and/or the second pumping chamber. 
     
     
       6. Multistage pump body according to  claim 1 , wherein the leak-tight conduit comprises at least one inlet for the cooling liquid and at least one outlet for the cooling liquid. 
     
     
       7. Multistage pump body according to  claim 1 , having a first side and a second side opposite the first side with respect to the axial passage, the connecting duct passing on the first side of the multistage pump body, the multistage pump body delimiting another connecting duct putting the outlet of the first pumping chamber into communication with the inlet of the second pumping chamber, this other connecting duct passing on the second side of the multistage pump body. 
     
     
       8. Multistage pump body according to  claim 1 , wherein the connecting duct is a first connecting duct, the multistage pump body comprising a third pumping chamber and a second connecting duct which is a duct putting an outlet of the second pumping chamber into communication with an inlet of the third pumping chamber, the heat-conducting wall being a first heat-conducting wall, the multistage pump body comprising at least a second heat-conducting wall, this second heat-conducting wall partially delimiting the second connecting duct and having an external surface on the outside, at least a portion of the second connecting duct passing between this external surface of the second heat-conducting wall and the leak-tight conduit. 
     
     
       9. Multistage pump comprising the multistage pump body according to  claim 1 , the external surface of the heat-conducting wall being outside of the pump. 
     
     
       10. Multistage pump according to  claim 9 , further comprising at least a first rotor to produce a displacement of gas downstream in the first pumping chamber, at least a second rotor to produce a displacement of gas downstream in the second pumping chamber, and a rotating shaft carrying the first and second rotors. 
     
     
       11. Multistage pump according to  claim 10 , said multi-stage pump being a lobe pump or a claw pump or a gear pump and comprising at least another first rotor in the first pumping chamber, at least another second rotor in the second pumping chamber and another rotating shaft carrying the other first and second rotors, the first rotor and the other first rotor being adapted to produce a displacement of gas downstream in the first pumping chamber by being driven in opposite directions, the second rotor and the other second rotor being adapted to produce a displacement of gas downstream in the second pumping chamber by being driven in opposite directions. 
     
     
       12. Multistage pump body according to  claim 1 , further comprising a rotating shaft, wherein said portion of the leak-tight conduit is disposed partially around the rotating shaft.